Show commit audit status in repository history tables, including merge commit lists

Summary:
Fixes T6024. Ref T12121. Currently, we show build status in commit history tables; show audit status alongside it.

Also:

• Change the "Author/Committer" header to just "Author"; I think it's reasonably obvious what "x/y" means (if you can't guess, you can click the commit and likely figure it out) and this gives us a little more space.
• Make the audit list look more like the corresponding list in Differential, with similar formatting.

Test Plan:

• Viewed history of a repostiory, saw audit status.
• Viewed a merge commit, saw audit status in the list of merged commits.
• Viewed a commit search results list.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12121, T6024

Differential Revision: https://secure.phabricator.com/D17227